This “device for teaching swimming,” patented by James Emerson in 1896, teaches good technique mechanically. The teacher places the machine in a swimming pool or open water, the student climbs aboard, the teacher turns crank handle 13, and the machine guides the student through the motions of swimming, “these arm movements being so nearly like those performed by an actual swimmer that the beginner who has these movements mechanically imparted to her arms thereby shortly acquires the swimming arm stroke.” What could go wrong?